1. Field of the Invention
This invention relates to a telephone device having a function to transmit position determination information obtained by determining the present position, to a device existing in the surrounding area.
2. Description of the Related Art
Devices which calculate and apply the present position by using the Global Positioning System (GPS) or by using a technique for determining the present position in accordance with a base station signal of a portable telephone or the like have already been made commercially available.
In the position determination technique based on the GPS, using a C/A (coarse/acquisition) code included in L1 radio waves with a carrier frequency of 1575.42 MHZ sent from three or more of 24 satellites orbiting at an altitude of approximately 20,000 km, the distance between a mobile unit and the satellites is found, thus calculating the position of the mobile unit.
In the technique for calculating the present position by receiving a signal of a portable telephone base station, the distance between the base station and a mobile unit is calculated from the phase difference of radio waves and the present position is calculated by using triangular survey on the basis of this distance, as disclosed in the Japanese Patent Application No. 2001-45549 and the Japanese Publication of Unexamined Patent Application No. H10-322752.
Meanwhile, many of the commercially available devices are equipped with an internal unit capable of measuring the present position, but these devices do not enable users to consciously send the present position to devices in the surrounding area.